


Let It Flow

by dracoqueen22



Series: Number One Crush [12]
Category: Transformers Generation One
Genre: Discussions of Previous Kinks, M/M, Mentions of previous rapeplay, Shower Sex, Sticky Sexual Interfacing, Twincest, Urophagia, Urophilia, Watersports
Language: English
Status: Completed
Published: 2016-11-20
Updated: 2016-12-02
Packaged: 2018-09-01 02:21:14
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 5
Words: 15,600
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8603455
Author URL: https://archiveofourown.org/users/dracoqueen22/pseuds/dracoqueen22
Summary: Sunstreaker’s newest, dirtiest secret tests the limits of what Sideswipe is willing to do for his brother even after Ratchet helpfully provides some context. But what comes next brings all three closer than they have ever been.





	1. The Discovery

**Author's Note:**

> So. This. I've been working on this for quite some time and debating on whether or not I would actually post it for weeks until I just decided, ya know, fuck it. Don't like; don't read and all that, right?
> 
> Anywho, this started out as a brief ficlet to curiously explore a rare kink and then it blossomed into five parts of character study, relationship study, and in-depth exploration of said kink. Heed those tags. And enjoy!

The idle stirrings of pleasure while in the middle of a shift were nothing new. Sideswipe had learned to ignore them. If Ratchet and Sunny wanted to canoodle while he was stuck staring at the monitors, all the better. That just meant they owed him one – or several if his shivering spark was any indication – by the time he got off-shift.  
  
Sideswipe's backstrut tingled. He fought off a wave of heat and stared harder at the monitor. He wondered what on Earth Ratchet was doing to Sunstreaker to make him so darned aroused. Fisting him again, perhaps? Though Ratchet usually didn't indulge in that in the middle of a work day.  
  
A blow job? Ratchet was pretty good at that. Or were they experimenting with bondage again? Sunstreaker did look gorgeous all trussed up and desperate.  
  
Sideswipe grinned to himself. He wished they weren't playing just so he could open up the bond and poke his twin to see what was going on. But he knew once he tapped into the bond, the floodgates would open, and he wouldn't be able to help himself.  
  
One time overloading in public to the unamused gimlet optic of Red Alert was enough for Sideswipe. He refused to overload on shift again.  
  
Sideswipe leaned on an elbow and stared harder at the monitor. He needed to focus. He needed to pay attention. He needed to--  
  
_“Sideswipe!”_  
  
He startled and nearly fell out of his chair. He scrambled at the table to keep himself upright, chair legs screeching across the floor.  
  
Trailbreaker snickered behind him. “Fall asleep again, Sides?”  
  
“No!” he said, indignantly. He snuck a glance at Ironhide who gave him a long look of disapproval. “I swear!”  
  
_“Sideswipe!”_  
  
He cringed and tapped at his comm. “Sorry. Yon Hatchet calls,” he said, by way of apology.  
  
Sideswipe righted himself in his chair, planted his gaze on the monitor, and accepted the surly shout blasting across his comms.  
  
_“Yes, dear?”_  
  
_“I am trying to rewire a very complicated leg assembly_ ,” Ratchet hissed, and wow did he sound irate. “ _Will you cease self-servicing in the middle of the day. **Again**_.”  
  
Sideswipe cycled his optics. “ _What_?” He looked over each shoulder, at the amused faces of his fellow shift-mates, and returned his attention to the monitor. “ _Ratchet, I'm on duty right now. Remember?_ ”  
  
Silence.  
  
“ _Ratchet?”_  
  
“ _If it's not you_ ,” Ratchet said with an audible grump. “ _Then why do my circuits feel like they are ablaze? Is this another game?”_  
  
“ _No! I would have told you if it was. Cross my spark!”_  
  
Sideswipe cycled a ventilation and rubbed at his forehead. It wasn't him. And it wasn't Ratchet. Which meant…  
  
He knew the moment Ratchet had drawn the same conclusion because the medic drew in a sharp ventilation. Sideswipe's array pinged him desire as his processor supplied images.  
  
Sunstreaker. Self-servicing. Oh, but what a rare treat. And he was missing it for monitor duty of all things.  
  
Sideswipe groaned and banged his head against the table. Sunstreaker could be a show-off when he was in the right mood, but try to get him to self-service for show, and he blushed and trembled like a virgin. It was utterly adorable and so fragging hot.  
  
“ _What in Primus' name is he doing?_ ” Ratchet demanded with a low growl Sideswipe knew all too well.  
  
That was Ratchet's 'I'm aroused, and I'm not supposed to be and as usual, I blame Sideswipe' growl. Except this time, he should be blaming Sunstreaker.  
  
“ _I don't know_ ,” Sideswipe replied. “ _How's about I ping him and ask?”_  
  
“ _You do that. I need to concentrate here_!” Ratchet huffed, and the comm went silent.  
  
Concentrate, huh? Somehow, Sideswipe doubted either of them were going to be doing any kind of concentrating anytime soon. Not with such a delicious image in the back of their processors. What was Sunstreaker doing? Stroking his spike? Using one of their toys in his valve? Both?  
  
Hnnnngh.  
  
Sideswipe licked his lips, braced himself, and pinged his brother's comm. “ _Hey, Sunny? Whatcha doing?”_  
  
“ _Nothing_!”  
  
And that, dear friends, was a Sunstreaker snarl. It was so fast, so violent, that Sideswipe's internal comm rattled.  
  
It was also a lie.  
  
Sideswipe shifted his weight, telling his spike to heel. “ _Then care to tell me why I'm feeling all kinds of excited over here on monitor duty?”_  
  
“ _Because you're an interfacing addict,_ ” Sunstreaker snapped. “ _Now leave me alone. I'm busy._ ”  
  
Wow. Going for the big guns there, bro.  
  
Sideswipe rapped his fingers on the table. “ _Or, and I'm just spitting in the wind here, or it's cause you just overloaded, and I felt it and Ratchet felt it, and you know, bro, we're just wondering. Whatcha doing and can we join?”_  
  
“ _I'm not doing anything. Frag off_!”  
  
The comm went silent, leaving Sideswipe to blink at his monitor in surprise. Well, that was, hmm, not a first, but highly unusual. In fact, the last time he'd acted like this, Sunstreaker had been hiding that he wanted to try something new with Ratchet and didn't know how to bring it up.  
  
Sideswipe sighed and decided to leave well enough alone. For now. At least until he was off-shift. Then he could do some research, figure out what had Sunstreaker's gears in a knot. In fact, he was going to recruit Ratchet's assistance this go round.  
  
Sideswipe's spinal strut itched. He blinked and registered the looming presence on his lefthand side. Planting a smile on his face, Sideswipe looked up into an infamous Ironhide glower.  
  
“Something wrong?” Sideswipe chirped.  
  
“Flirt on your own time,” the old warrior growled and leaned a bit closer, looming without trying. “There're worse punishments, Sideswipe.”  
  
He wilted. “That there are.” His smile faltered, and he turned back toward the monitor. “Which is why I'm going to be paying close, close attention to this screen.”  
  
“Good. Cause I'm watchin' ya.”  
  
Of course he was.  
  
Sideswipe ducked his head, sagged his shoulders, and pretended to be fully interested in the endless cycle of surveillance cameras. Sir, yes, sir. Paying attention, sir.  
  
And not, for instance, crafting a quick message to Ratchet. There was a mystery afoot, and Sideswipe intended to solve it.  
  
Because every time Sunstreaker got one of these ideas in that fool head of his, it was a guaranteed good time for Ratchet and Sideswipe, too.  
  
Win-win-win.  


 

0o0o0

  
  
Sideswipe didn't bring up the conversation to Sunstreaker, and told Ratchet not to either. They both pretended that nothing had happened. They let Sunstreaker be.  
  
Well, not entirely.  
  
There was one certain way to catch a Sunstreaker. One only needed the proper bait. A nice deep-clean, paint strip, repaint and wax was perfect. Wave said opportunity under Sunstreaker's nasal ridge, and he'd follow you wherever you wanted him to go. Even if you weren't so good at laying down a sly invitation.  
  
Ratchet was not good at subtle or sly.  
  
But he did manage to get Sunstreaker out of their shared quarters without arousing any suspicions on Sunstreaker's part. Then again, Sunny could be pretty dense sometimes.  
  
With both of them gone, Sideswipe was free to snoop. Privacy was just not a thing between twins, but more than that, he knew Sunstreaker. Sunny would keep hiding whatever this was forever and ever, hoping the whole time Sideswipe would find out on his own and make him confront it.  
  
Sunstreaker was the definition of “pretend it doesn't hurt until someone proves it does.”  
  
It was the same with the fisting and the sounding and the double-penetration. And they'd all had a good time in the end, right?  
  
Right.  
  
So. Snooping.  
  
Sideswipe poked around Sunstreaker's datapad collection, only browsing the ones that looked to be recently activated. None of them produced anything of note, however. Which wasn't surprising. Sunstreaker really wasn't the sort to self-service to some kind of visual aid. But he'd had to be fantasizing about something, and not just the usual ones either. He wouldn't have acted so offended if he was just imagining Sideswipe swallowing him or Ratchet sounding him again.  
  
Sideswipe's gaze landed on the computer workstation he and Sunstreaker shared. It was different than Ratchet's, which was on a more secure network and contained stuff he and Sunny weren't allowed to access.  
  
No. Sunstreaker wasn't the sort to watch or read erotica. But he was the kind to do research.  
  
Sideswipe grinned and threw himself into the rolling chair. It sent him feet away from the console and he had to drag himself back by his feet. He quickly logged into the system using Sunstreaker's pass codes and brought up the browser.  
  
Sunstreaker was smart. He'd closed all of the windows and tabs, perhaps trying to hide his research in a hurry.  
  
But he wasn't smart enough. Because when Sideswipe checked, Sunstreaker hadn't cleared the browser history. Recently closed tabs still listed about twelve websites. Which meant not only could Sideswipe view those, but also anything previously viewed on those tabs.  
  
He shook his head. You'd think after all these decades of watching the master, Sunny would have learned a trick or two. Poor amateur.  
  
Sideswipe started to skim. Most of it was boring stuff, artistic research and the like. There was a lot of information about perspective and shading and blah, blah, blah. Sideswipe understood some of it, but for the rest, the context was lost on him. And he was pretty sure this wasn't the stuff that had affected Sunstreaker.  
  
But then one of the tabs opened to a pornsite. A _human_ pornsite at that. This was one Sideswipe had never visited. He'd seen the advertisements for it popping up on some other vids when he'd gone looking for ideas online, but he hadn't managed to wander this direction yet. Which was odd enough. Sunstreaker didn’t usually go looking at human porn. He proclaimed to find it disgusting.  
  
Sideswipe's optics widened.  
  
Sunstreaker hadn't just been browsing. He'd come here with some specific search terms. He'd typed in at least three the browser had saved, one of which was unfamiliar to Sideswipe, and the other two he thought he knew, and hoped he didn't.  
  
'Watersports.'  
  
'Pissplay.'  
  
'Golden shower.'  
  
Clicking on the highest rated video for the search terms confirmed Sideswipe's suspicions. He exited out of the tab just as quickly, spark pounding in his chestplate.  
  
That was… not what he expected.  
  
He'd heard of this kink before. He'd seen it in passing. The very idea of it had not interested him, so Sideswipe had never given it a second thought. It was the last kink he'd ever expect his cleanliness-obsessed brother to develop an interest in.  
  
Wasteplay was, well, Sideswipe admitted he'd try anything once, but it was just so… dirty. Sunstreaker hated to be dirty. He hated all things unclean. Why would Sunstreaker want something like this? And which part?  
  
Sideswipe chewed on his lower lip and braced himself. He dove back into the fray, clicking on a few videos whose links indicated they'd been viewed before. Though that didn't help him figure out which one Sunstreaker liked the most.  
  
Did he want someone to eliminate waste on him? In him? In front of him? Did he want to do it to someone else?  
  
Sideswipe cringed. Every video was different. In fact, the only defining characteristic was that they contained the same kink. How it was enacted was a different matter. He couldn't even claim 'enjoyed' because frag, that one female right there did not look like she was participating willingly.  
  
Sideswipe's comm pinged.  
  
“ _Well_?” Ratchet demanded.  
  
“ _I found something_ ,” Sideswipe replied and did Sunstreaker a favor – he cleared the browser history. No need for Teletraan to store this. “ _I'll tell ya later though. How's Sunny_?”  
  
Ratchet sent a soft chuckle through. “ _I'll send you the pics_.”  
  
Sideswipe smiled despite himself. If Ratchet was taking pictures, then Sunstreaker was being adorable and charming, and Sideswipe couldn't wait to see.  
  
He and Ratchet would have a talk later, perhaps when Sunstreaker recharged or was on shift.  
  
This definitely warranted a discussion or two.  


 

****


	2. The Discussion

**Summary for the Chapter:**

> In which Sideswipe tells Ratchet what's up, and Ratchet has to give Sideswipe a lesson in biology.

**Notes for the Chapter:**

> In which I couldn't just write a kink without trying to reason out why said kink exists because who needs a quick kinky oneshot, hmm? Noooo, I gotta explain it. *facepalm* 
> 
> Next part is the good stuff.

Sunstreaker fell into recharge long before Ratchet and Sideswipe, partially because he actually had the earliest shift the next day, and partially because Ratchet and Sideswipe planned it that way. All the better to plot and discuss without Sunstreaker listening in. Sometimes, if one didn’t chose their words carefully, it would be too easy to offend Sunstreaker.   
  
He had a terrible affliction. Sometimes, he only heard half of what you said and never what you meant. Rather than deal with a potential hissy fit, Ratchet decided to cut out the drama and have this conversation incognito.   
  
So. Sunstreaker was conked out in the berth, fully sated, freshly polished, and free to start his shift in the morning in a good mood. Meanwhile, Ratchet and Sideswipe were clustered in the main room, their voices hushed, and one optic focused on the door to the berthroom. Sideswipe promised he was watching out over the bond, too.   
  
“All right, brat. What’s on your brother’s processor this time?” Ratchet asked as he tried to lean back in his chair. He was missing out on some good recharge right now.   
  
Sideswipe’s face lost a touch of color. “Well,” he said, and rubbed the back of his neck. “It’s kind of the last thing I expected.”   
  
Great. Now Sideswipe was being vague.   
  
Ratchet rubbed his chevron. “How about you not play the mystery and just tell me, Sideswipe? Trust me, there’s nothing you or your brother could look at that I’ve never seen before.”   
  
“You say that but I guarantee someday, we’ll shock you,” Sideswipe muttered, but he crossed his arms over his chestplate and rallied. “It’s wasteplay.”   
  
Ratchet blinked. He wasn’t sure what he expected, but that certainly wasn’t it. “Huh,” he said. He rolled the revelation around in his processor, poked at it from all angles, until he decided that, well, he wasn’t surprised.   
  
“Huh? Is that all you have to say?” Sideswipe demanded. Clearly, he was the one using up all the surprise for this disclosure.   
  
“Yes. For now.” Ratchet sat back in his chair. “I suppose it makes sense in a way. Though it depends which aspect of it interests him the most.” Like most kinks, there were many different ways to indulge in wasteplay. It was impossible to guess which of them Sunstreaker was drawn to.   
  
Sideswipe rocked back and forth on the chair and stared at Ratchet as though he’d never seen him before. “Why aren’t you bothered by this?”  
  
Ratchet cycled a ventilation. “Because nothing involving the two of you surprises me anymore,” he said. “What kind of videos was he watching?”   
  
Sideswipe made a face. “All of them,” he said, and squirmed in his chair. “People getting eliminated on or in them. Stuff where people soaked their clothes. And stuff where they, um, you know...” He trailed off, color stealing into his faceplate.   
  
Ratchet arched an orbital ridge. “No, I don’t know.” He was careful to keep his tone neutral, though a part of him was intensely amused. So this, of all things, was what would make Sideswipe squirm. It was kind of adorable, actually.   
  
“Augh, you’re torturing me like this on purpose,” Sideswipe moaned dramatically and sank down further in his seat, as though he could hide from the truth. “They were licking it and drinking it and--” He broke off with a shudder. “Ewww.”   
  
“Ewww,” Ratchet repeated flatly. “After everything we’ve done together, all of the weird kinks you both have asked for, this is the one that makes you cringe.”   
  
“Yeah. Because it’s gross,” Sideswipe retorted.   
  
Ratchet narrowed his optics. “You've licked my transfluid out of Sunstreaker's valve before.”   
  
Sideswipe blinked. “So?”   
  
“Just last week, you licked your _own_ transfluid off the floor,” Ratchet pointed out with an audible huff. While that scene had been particularly hot because Primus did Sideswipe know how to put on a show, it did present a bit of a flaw in Sideswipe’s logic.   
  
Sideswipe squirmed in his chair. “Yeah, but that's different.”   
  
“It's not, really.”   
  
“Of course it is!” Sideswipe threw out his arms, making wild gestures that pointed to nothing and everything all at once. His field surged out, a tangled morass of emotions. “Transfluid is… transfluid. And that is… waste stuff.”   
  
All at once, Ratchet remembered the Twins had no formal education or training. That they had learned from the “school of hard knocks” as the humans would say, and that it should come as no surprise Sideswipe should have this sort of reaction.   
  
“Waste stuff,” Ratchet echoed and sighed. He pinched his nasal ridge, expecting a headache shortly. “Just what do you think transfluid is, Sideswipe?”   
  
His red lover blinked at him. “Robot jizz?”   
  
Ratchet silently mouthed the phrase, but couldn't bring himself to repeat it aloud. He stared at Sideswipe and sighed again. Heavier this time. He wondered if he could sigh his exasperation right out of him.   
  
“In a crude, inaccurate manner, yes,” Ratchet finally said when Sideswipe continued to blink at him innocently. “But also, transfluid is a slurry of extraneous materials that your frame may need at some point, but isn't willing to expel immediately.”   
  
Sideswipe rocked back in his chair. “Huh?”   
  
Oh, Primus. Ratchet really was going to have to start at the beginning, wasn't he?   
  
“Different mechs need different materials, but we all drink the same energon, yes?” Ratchet pointed out, hoping he could lead Sideswipe to the proper understanding.   
  
“Yes,” Sideswipe said, dragging out the syllables. He sounded like a child who was being scolded by his parents.   
  
Ratchet rubbed his chevron. “Ever wonder why our transfluids taste different? Why mine is bitter and yours and Sunstreaker's aren’t?”   
  
“No…?”  
  
Ratchet worked his jaw and gestured to the chair. “Get comfortable. This is going to take a while.”   
  
Sideswipe made a face. “Awww. Are you about to lecture me?”   
  
“Yes. Because your education is lacking.” Ratchet held up a hand to forestall the coming argument. “Yes, I know, you would have learned if you had the chance. So here’s your chance. Sit.”   
  
Sideswipe sat, dropping back into the chair with a graceless flop. “Fine.” He couldn’t have looked more petulant if he tried.   
  
“Good.” Ratchet sat back and rubbed at his faceplate. “If you don’t want to indulge Sunstreaker, that’s fine. But I’m not letting you walk out of here with a huge misconception of what your frame does on a daily basis, understand?”   
  
“I’d do anything for Sunstreaker!” Sideswipe argued, indignant. His optics widened, his entire frame going stiff.   
  
“I know you would.” And sometimes, that was precisely what got them into trouble. Ratchet dropped his hand, giving Sideswipe a level look. “But something tells me he’s been hiding this for months. It was hard enough to come to me about the fisting, and about the sounding, and now this? How do you think he’d react if you wrinkled your ridge and said ‘ew’ to his face?”   
  
Sideswipe’s mouth opened and then shut, visibly chastened. “It was just a surprise is all. I’d never tease him about it!” One foot kicked out, heel scuffing the floor.   
  
“I know.” Ratchet gentled his tone. Sideswipe, like his brother, often fought back if he felt cornered. “It may be that this is just one of those kinks for your brother that looks good in theory, but you’d never actually want to try in real life. Until we know either way, however, I need you to not… well, not be you.”   
  
Sideswipe blinked and tilted his head. “Ratchet, would you… I mean, are you interested in this?”   
  
Ratchet couldn’t decide if Sideswipe sounded surprised or appalled. He settled for shrugging dismissively. “I’ve done it before,” he admitted.   
  
Sideswipe stared at him. There was judgment in the look, though he didn’t have any room to talk.   
  
“It doesn’t interest me like that!” Ratchet snapped and huffed a ventilation. “But I had a partner who did, and watching how he reacted to it, that was enough for me. That made it worth it. You don’t really think your brother and I enjoyed pretending to rape you, do you?”   
  
Sideswipe flinched. “You could have said 'no'.”  
  
“We didn't because it was something we wanted to do for you. Because you asked.” Ratchet crouched in front of him, resting his hands on Sideswipe’s knees. “I love you. Sunstreaker loves you. Because we love you, we decided together that we would try because you asked. That was enough.”   
  
Sideswipe’s gaze fell. “Oh.”   
  
“I’m not saying that this is that,” Ratchet continued, his fingers pattering a rhythm on Sideswipe’s armor. “If you don’t want to do this, that’s fine. I’m not going to make you or guilt trip you into it. I want us all to have a good time, and I know Sunstreaker wouldn’t want you to feel obligated.”   
  
“I know.” Sideswipe ex-vented loudly and squirmed in his chair. “It’s not that I don’t want to – okay, that’s a lie, I’m not at all interested. But more than that… isn’t it dangerous?”   
  
“And that is where the education comes in,” Ratchet said, and patted Sideswipe’s knee. “Listen and then decide. Can you do that?”   
  
Sideswipe nodded. “Yes.”   
  
“Good.” Ratchet pushed back to his feet, ignoring the creak in his knees, and returned to his chair. “Right. So the beginning.” He rubbed at his chevron, feeling the edge of the headache. “We all drink energon. It’s the liquefied version of a raw ore that we all use to power our frames, and is kind of like a nutrient chunk all in one. We’re still not entirely sure what all is in energon, to be honest.”   
  
“So it’s like a granola bar that’s been made into a smoothie?”   
  
Ratchet cycled his optics. He worked his jaw. “Sure,” he said with a wince. “Something like that. Anyway. Frames are different. Altmodes are different. We all have different needs for our frames. Some of those materials are superfluous for us. Some of them are so necessary that we need to store it in between servings.”   
  
Sideswipe leaned forward, bracing his elbows on his knees. “So we store it in our transfluid?”   
  
“And in our waste tanks. Except it’s not really waste, more like excess materials that could potentially become useful, but if not, expelling them isn’t a waste,” Ratchet explained.   
  
Sideswipe worked his jaw. He chewed on his bottom lip. “Then why do we call it waste?”   
  
“Because it’s still extraneous, and it’s still wasted materials,” Ratchet said and held up a hand, forestalling the inevitable question. “Don’t get me wrong, waste fluid is still a slurry, a mix of energon stripped of its charge, processed materials and superfluous ones. But...” And here he shrugged. “One mech’s waste might contain valuable materials for a different frame-type.”   
  
Sideswipe opened his mouth, closed it, opened it again. He shifted in his chair, leaned back and then forward. “So you’re telling me,” he said, slowly and carefully. “You’re saying, probably, that theoretically, drinking someone else’s waste could be a benefit?”   
  
“Depending on the frametype, yes.” Ratchet rubbed at his chevron. “It’s still better to drink freshly processed energon because it’s a drain to re-process and try to filter out what little use is left.” He waved a dismissing hand. “Where do you think the waste goes when you eliminate it?”   
  
Sideswipe shrugged. “I dunno. I never thought about it.” He scratched at the side of his nasal ridge. “Why would I?”   
  
“Recycle and reclamation. It’s sanitized, filtered, and stored, depending on what use there is. Anything left over is then disposed of.” Ratchet leaned back with a sardonic grin. “That’s the benefit of being metallic, I guess. We’re all re-usable.”   
  
Sideswipe made a face. “That’s disgusting.”   
  
“It’s truth.” Ratchet shrugged. “Especially in the middle of a war. You can’t be too choosy about the things that save your spark.”   
  
Sideswipe’s nasal ridge twitched. “Maybe not. But sometimes, you know, ignorance is bliss.”   
  
“It can be,” Ratchet admitted and leaned back in the chair, crossing his arms over his chestplate. “So. Now you know.”   
  
“Yeah. Still kinda wishing I didn’t.” Sideswipe scraped a hand down his face and audibly ex-vented. “I mean, Sunny doesn’t know this anymore than I did, and yet he’s still interested? What does that even mean?”   
  
Ratchet shook his head. “I don’t know, Sideswipe. That’s something you’d have to ask him. But the real question here is whether or not you are willing to try.”   
  
“Of course I’ll try!” Sideswipe’s tone was indignant, and he followed it up with a scowl. “I mean, it’s Sunny. I’d do anything for him. I just gotta wrap my head around it is all.” He looked away, one finger scratching at the side of his nasal ridge.   
  
Ratchet unfolded his arms and leaned forward. “Be sure, Sideswipe. I have no problems indulging him on my own, and I don’t want you showing up and for a single second, making him believe he’s disgusting.”   
  
Sideswipe visibly twitched. His mouth opened and closed. “I can do it,” he said, finally.   
  
Ratchet gave him a long look. He wasn’t certain Sideswipe actually was sure, but they could at least set their plans in the future, to give Sideswipe more time to get used to it.   
  
“All right,” Ratchet said, and threaded his fingers together. “Let’s talk plans.”


	3. The Surprise

**Summary for the Chapter:**

> In which Sideswipe is acting weird-er, Sunstreaker finds out why, and the fun begins.

**Notes for the Chapter:**

> Herein is where the truly NSFW kink starts. Last chance to back away slowly. ;)

Sideswipe was being weird. Well, weird-er.   
  
Sunstreaker narrowed his optics and glared in his twin’s direction, not that Sideswipe noticed. He continued to squirm in his chair like a child with a secret, one end of a stylus between his lips as he nibbled on it, and his attention focused on his datapad. Sunstreaker didn’t know what he was looking at.   
  
The chair squeaked as Sideswipe wriggled again.   
  
Sunstreaker sighed and put down his own stylus. So much for focusing on his sketch. All of that movement in his peripheral vision was too distracting.   
  
“What the frag’s the matter with you?” Sunstreaker demanded, reaching out and poking Sideswipe with his field.   
  
His twin blinked at him owlishly. “Huh?”   
  
“You keep… fidgeting.” Sunstreaker made a vague motion to encompass all of Sideswipe’s recent behavior.   
  
Sideswipe blinked again. “I am?” He tried for innocent. He failed.   
  
Sunstreaker’s optics narrowed. “What’s going on?”   
  
“Nothing!” And that sounded too hasty. But Sideswipe did put his datapad and stylus down and rise to his feet. “I gotta go.”   
  
“Go where?”   
  
“Out.” Sideswipe backed toward the door, throwing a thumb over his shoulder. “To the facilities. The washracks. The things. You know.”   
  
Sunstreaker’s suspicions grew. “I just waxed you this morning. What do you need a wash for?” He shoved to his feet, spacing his datapad as he stalked toward Sideswipe and grabbed his shoulders. He spun his brother around in circles. “What did you do to yourself already?”   
  
“Nothing. I’m perfect. Sheesh.” Sideswipe batted his hands away and danced out of Sunstreaker’s grasp. “This has nothing to do with my paint.”   
  
“Then what is it?” Sunstreaker demanded. He tapped into the bond, but Sideswipe’s end was quieter than usual, with only the dimmest sense of discomfort and urgency to give Sunstreaker some kind of idea.   
  
“I have to empty my tank!” Sideswipe huffed and threw his hands into the air. “There. Primus allmighty, Sunstreaker. Can I go and do that on my own or do I need your help with that, too?”  
  
Sunstreaker went still. Utterly still. Sunstreaker stared at Sideswipe, who appeared both annoyed and indignant, as something squirmed deep in his belly.   
  
No.   
  
It was only meant in jest.   
  
No. He would not activate his fans. He would not let his processor run away with the possibilities. He would not.   
  
Sunstreaker closed his hands into fists. “Of course you don’t,” he snapped, and spun on a heelstrut. “If that’s all it is then just say so, you idiot.” His spark raced and he worried, what if he hadn’t been as careful as he thought.   
  
“Well, I wouldn’t have to if you didn’t insist on knowing everything I do,” Sideswipe retorted and Sunstreaker could all but hear him roll his optics. “Besides, it’s embarrassing.”   
  
Sunstreaker dropped down into his chair and buried his face behind a datapad, just so he wouldn’t have to look at his stupid twin. “You? The master of all things ridiculous finds something embarrassing. Perish the thought.” He flicked a hand at Sideswipe without looking at him. “Go. Take care of it.”   
  
This was him. Very uninterested. Totally focused on his datapad and only his datapad. The one he hadn’t even turned back on yet, but Sideswipe didn’t know that. He didn’t have to know that.   
  
“But, well, what if I _did_ need help?”   
  
Sunstreaker froze. His ventilations stalled.   
  
“Then you should call Ratchet,” he said, without looking up, manually telling his ventilations to start again. A heat flushed through his frame. “He’s the medical expert here, not me. And it sounds like you have a personal problem.”   
  
Sideswipe huffed. “Ratchet’s busy.”   
  
“Then ask Hoist.”   
  
“He’s busy, too.”   
  
“First Aid isn’t.”   
  
“But that would be even more embarrassing.” Sideswipe’s tone approached a whine, a theatrical one.   
  
Sunstreaker worked his intake. “I don’t know what you think I can do about it then,” he retorted.   
  
Footsteps. Movement in his peripheral vision and then suddenly, Sunstreaker had a lapful of red Lamborghini, and his datapad ended up crushed against his chestplate. Sideswipe’s arms fell over his shoulders as Sideswipe pressed their foreheads together.   
  
“I don’t think you’re paying attention, bro,” Sideswipe said with a little wriggle of his hips that both Sunstreaker and Ratchet never failed to be seduced by. “Cause I have a problem and I’m pretty sure you’re the only one who can solve it.”   
  
Sunstreaker’s gaze skittered to the side. “You’re being ridiculous. If you wanted to frag, you could’ve just said so.”   
  
“I’m not talking about fragging.” Sideswipe’s hips wriggled again. “Well, okay, that can come after.”   
  
“You’re not making any sense!” Sunstreaker snapped and shoved at his brother’s chestplate with his hands and datapad. His spark shivered, his tank twisting into a knot. “Get off me.”   
  
Sideswipe’s thighs tightened on his, arms staying around Sunstreaker’s shoulders. “Oh, ho. That’s a lie and you know it is. You know exactly what I’m talking about, Sunshine.” He rolled his hips forward. “And if the bond is telling me anything, it’s showing me just how much you know.”   
  
Sunstreaker gnawed on the inside of his cheek. “Why are you teasing me, Sides?”   
  
“That is the last thing I’m doing.” Sideswipe’s voice turned softer, his field stroking along Sunstreaker’s with warmth and reassurance. “I’m making an offer. One that I think you’ve been interested in for a while, though you haven’t said anything.”   
  
Sunstreaker’s engine whined. He clutched the datapad harder. He was right all along. “I didn’t clear the browser history,” he whispered in realization.   
  
Sideswipe pressed a kiss to the tip of his nasal ridge. “No, you didn’t.”   
  
He dimmed his optics. “Are you serious?”   
  
“When it comes to you, always.” Sideswipe pressed another kiss on his forehead. “Ratchet’s in on it, too. In fact, he kind of told me to wait, but--”  
  
“You’ve never been good at waiting,” Sunstreaker sighed. He couldn’t bring himself to lift his gaze.   
  
“Nope!” Sideswipe said cheerfully, giving another wriggle. In fact, he was a mech in constant motion.   
  
Maybe the need to empty his tank wasn’t a lie after all. He kept squirming as though trying to distract himself, or perhaps, shift the pressure away from his full tank.   
  
“Come on, Sunny. Don’t you want to give me a hand?” Sideswipe purred, nipping at Sunstreaker’s head vents.   
  
Sunstreaker worked his intake. “You don’t think it’s… gross?”   
  
Sideswipe sat back a little, one arm shifting so that his hand gripped Sunstreaker’s jaw. He pulled Sunstreaker’s head up, forcing their gazes to meet.   
  
“Listen,” he began, and it was with his serious face, the one few knew he was capable of having. “Ratchet sat down and gave me a lecture, a long lecture. And yeah, maybe I don’t get the appeal, but you will never be ‘gross’ to me, no matter what. Got me?”   
  
That wasn’t entirely reassuring.   
  
Sunstreaker gnawed on his bottom lip, the shame still creeping in at the edges. “You don’t have to do it just ‘cause I want to,” he said.   
  
“I know that.” Sideswipe pressed their foreheads together, his ex-vents ghosting over Sunstreaker’s face and intake. “But I can try. Who knows? I might even like it. The fisting turned out pretty sexy, didn’t it?”   
  
It had. This was very true. But fisting was miles away from… from this.   
  
“I promise,” Sideswipe murmured, his thumb stroking over Sunstreaker’s chin. “Nothing you could ever want would make me love you less.” He dipped his head and captured Sunstreaker’s lips, initiating a soft kiss.   
  
Sunstreaker sighed into it, his spark rippling with a mix of anxiety and anticipation. He remained uncertain, but he trusted Sideswipe’s love for him.   
  
“Fine,” he said against Sideswipe’s lips, his insides coiling with expectancy. Numerous fantasies sprung back to life in the back of his processor.   
  
“Good. Then let’s go!” Sideswipe hopped to his feet, grabbed Sunstreaker’s hand, and tugged.   
  
Sunstreaker cycled his optics and didn’t budge. “Right now?”   
  
Sideswipe chuckled and squeezed his hand. “Yes. Right now. I mean, if you don’t want to do this now, that’s fine. Either way, my tank needs to be emptied. And soon.” His free hand rubbed at his lower left ventrum, and his smile drooped toward a grimace. “I may have accelerated the processing a little.”   
  
Sunstreaker rose to his feet, letting Sideswipe tug him toward the door. “Let me guess. You went against Ratchet’s advice and did something you weren’t supposed to do.”   
  
“Who? Me?” Sideswipe grinned at him, though it dipped at one corner. His tugging increased in earnest. “Would I do that?”   
  
Sunstreaker gave him a look, one that didn’t require words. But he let Sideswipe pull him out of their quarters and down the hall.   
  
“The washracks are that way,” Sunstreaker said, pointing behind them.   
  
“Yeah. I’m not using those.” Sideswipe tossed a wink over his shoulder. “We need privacy, don’t you think?”   
  
Heat stole into Sunstreaker’s face. He worked his intake. “Oh. Yeah. I guess.” He honestly didn’t want anyone walking in on what they were about to do. Whatever it was. He didn’t know which parts Sideswipe had seen and which he hadn’t, and Sunstreaker was too afraid to ask.   
  
“Where are we going then?” Sunstreaker asked.   
  
Sideswipe put a little dance in his step, but it was with less enthusiasm than usual. “Where else? Who do you think gave me codes to a private washrack?”  
  
Ratchet. Of course it was Ratchet. Sunstreaker would have to thank him later, once the anxiety stopped gnawing at his tanks. It left him waffling. Should he do this? Should he not?   
  
Sideswipe put more haste into his step, his hand attached to his abdominal armor as though that soothed the discomfort.   
  
“What did you do?” Sunstreaker demanded. “Drink a whole box of coolant?”   
  
Sideswipe grimaced at him. “Not in so many gallons. Just some kind of accelerant. I don’t know. I didn’t realize it would be this, um, quick.”   
  
Sunstreaker palmed his face. “Primus save me from idiot twins,” he muttered. “It’s called an accelerant for a reason, dumbaft.”   
  
“Well, I know that now,” Sideswipe drawled, only to brighten, his aft wiggling. “We’re here!”   
  
He towed Sunstreaker to a door, and put in the command code with eager jabs of his finger. The moment the door slid open, Sideswipe all but yanked Sunstreaker inside, his palm slamming the locking panel on the other side.   
  
“Ahh, privacy,” Sideswipe said, and finally let go of Sunstreaker’s hand, though the other still rubbed over his abdomen.   
  
It was indeed private. It was a single stall, could probably hold four average sized mechs comfortably. Sunstreaker could lay down within it if he wished, though he might have to draw up his knees. There was only the one entrance, further proving that it would be private, and as far as he could tell, no monitoring equipment.   
  
“So how do you want to do this?” Sideswipe asked, snatching Sunstreaker’s attention. He spread his hands and turned in a circle. “Should I just, uh...” He trailed off and made a vague gesture that Sunstreaker assumed was meant to illustrate him emptying his tank.   
  
Sunstreaker’s face heated. His gaze wandered to the wall. “I’m not sure,” he admitted, and scratched at the side of his nasal ridge. “I mean, it’s not like I ever thought it would actually happen.”   
  
“Yeah, but you fantasized about it, right?”   
  
The heat became an inferno. His engine whined. He nodded.   
  
“So tell me one of your fantasies then. We can do that.” In his peripheral vision, Sideswipe bounced on his heelstruts. “Or, you know, we could start out simple and you could just kiss me. Feeling a bit lonely over here, bro.”   
  
His fantasies?  
  
Sunstreaker wanted to go somewhere and hide. His fantasies were not fit for sharing. They were humiliating, gross, and most of them he wasn’t sure he wanted to ever experience in real life, much less tell his brother about them.   
  
He still wasn’t convinced Sideswipe knew what he was getting into when he made this offer. But kissing? That Sunstreaker could do.   
  
Sunstreaker pinned Sideswipe against the wall, his hands pressed to either side of Sideswipe’s chassis, and slanted his mouth over his twin’s. It was easy to kiss Sideswipe, easy to get lost in the press of their lips, the tangle of their glossa. Sunstreaker’s engine purred as the kiss deepened, and Sideswipe’s arms fell over his shoulders, tugging him close.   
  
Their frames collided, metal to metal, chest to chest. Sunstreaker shivered, feeling his brother’s spark pulse in sync with his. There was nothing in Sideswipe’s field but encouragement, affection, and the lingering sense of urgency.   
  
Nothing ventured, nothing gained.   
  
Sunstreaker eased out of the kiss and focused his attention on Sideswipe’s intake. He licked and nibbled the heated cables beneath his lips as Sideswipe gasped and clutched at his shoulders.   
  
Sunstreaker continued down, kissing Sideswipe’s chestplate, his headlights, and further still, until he could press his lips to Sideswipe’s belly. Somewhere to the right here was Sideswipe’s waste tank, and when he rested a hand against the armor, and gave it a push, Sideswipe groaned. His knees wobbled.   
  
“You’re really full,” Sunstreaker whispered, dropping to his own knees, his hands cradling Sideswipe’s hips.   
  
“I told you I was,” Sideswipe replied, and squirmed in Sunstreaker’s hold, his hips swaying from side to side. “Do you want me to--”  
  
Sunstreaker shook his head. “No. Not yet.” He looked up at Sideswipe, his glossa flicking over his lips. “Hold out as long as you can?”   
  
Sideswipe’s engine screeched. “I’ll – nnn – try.” More discomfort leaked into Sideswipe’s field, his squirming about as hot as the Pit.   
  
Sunstreaker’s mouth watered. He worked his intake. “Open up for me?” he asked, ex-venting hotly over Sideswipe’s panel.   
  
His brother shuddered, leaning harder against the wall as he scooched his feet further apart. But his panel did open, spike and valve both coming into view. Sunstreaker worked his intake again and pressed a kiss in greeting to Sideswipe’s anterior node. A low whine caught in his brother’s intake, hips jutting forward.   
  
“I can’t decide if I’m aroused or desperate,” Sideswipe admitted with a pant.   
  
“Probably both.” Sunstreaker dragged his mouth to Sideswipe’s spike, coaxing the unit out to play with both his denta and his glossa.   
  
Sideswipe’s spike emerged readily, willing to greet the mouth who knew it well. Sunstreaker smirked to himself and suckled on the tip, his glossa poking at the transfluid slit. Sideswipe shuddered, sliding a little further down the wall, his spike giving a happy pulse. It wasn’t fully pressurized, a little soft in the circumference, but Sunstreaker suspected that was because of the pressure on Sideswipe’s waste tank.   
  
Sunstreaker moaned around Sideswipe’s spike and gripped his hip harder. He freed one hand to tease at his brother’s valve, his fingers tickling around the rim and gathering up dribbles of lubricant. Sideswipe gasped and ground down on his fingers, his valve cycling needfully.   
  
“You keep… doing that...” Sideswipe gasped, and his head hit the wall with a thunk.   
  
Sunstreaker sucked harder on his spike, sucked it like he could pull the overload right out of Sideswipe. He slipped two fingers into Sideswipe’s valve, hooking them to rub mercilessly on the nodes behind his exterior nub, the ones that made his knees wobble.   
  
Sideswipe clutched at his head.   
  
“I’m not gonna be able to hold it,” Sideswipe said in a rush, a full-length tremor rattling his frame.   
  
Sunstreaker let Sideswipe’s spike fall from his mouth, rubbing the rounded tip against his cheek. “That’s fine,” he replied before taking Sideswipe’s spike back into his mouth, his own frame shivering.   
  
Heat coiled within him faster and faster. The pressure mounted in his groin until he couldn’t hold back anymore, his own panels popping and his spike surging free. It bobbed, cool air whisking across the tip.   
  
Sideswipe moaned, scrabbling at his head, his shoulders. His entire frame rattled as he attempted to hold onto himself.   
  
“ _Just tell me to stop if you don’t wanna do this_ ,” Sunstreaker said across the comm, unwilling to take his lips away from Sideswipe’s spike for even a moment. It throbbed on his glossa, as Sideswipe’s valve clamped hungrily on his fingers, trying to draw them deeper.   
  
Sideswipe answer was to gasp and buck his hips, his hands slamming against the wall. His backstrut arched, his vents roaring and rattling. Sunstreaker looked up, saw him in silhouette, and he was beautiful.   
  
“Sunny,” Sideswipe gasped aloud, his voice wreathed in static. “I’m gonna, I can’t, Sunny, I’m gonna-gonna-”  
  
Action replaced words.   
  
Sideswipe’s tank gave before his overload did. Sunstreaker’s hand latched onto Sideswipe’s hips as the first spurts of Sideswipe’s waste struck his glossa, and slithered down his intake. It was thick, oily, hot, sour. It was gritty and bitter, and Sunstreaker’s intake convulsed.   
  
He pulled off, coughing. Sideswipe didn’t stop. He couldn’t stop. The stream spurted on Sunstreaker’s face, his intake, it slithered down across his chestplate, it got into his seams. He felt it tickle against his cables, his struts, heard the pattering of it as it struck his armor, like a bitter rainfall.   
  
Sunstreaker’s fans roared, but he heard it through a tunnel. His glossa flicked across his lips, catching the bitter taste, and Sideswipe still shook and trembled, making the cutest sounds. Sunstreaker ignored the convulsions in his intake and took Sideswipe into his mouth again, his fingers shoving deep into Sidewipe’s valve. He fingered him aggressively, seeking out nodes with single-minded determination, his thumb rubbing hard on Sideswipe’s anterior nub.   
  
Sunstreaker’s tank rippled. The flow became a trickle, dribbling down his intake, over his glossa. The taste similar to his own but somehow not. It wasn’t pleasant by any definition. Like energon that had been left out, uncapped and unfiltered. Bitter and gritty, coating his intake like a spill of paint.   
  
It was disgusting.   
  
Sunstreaker moaned as the scent of it filled his olfactory sensors, clearly Sideswipe, but this, too. It was dizzying. It was on his armor, in his seams, soaking him all the way through. It formed a puddle beneath his knees. Sunstreaker’s spike throbbed, and his hand left Sideswipe’s hip before he could stop himself, wrapping fingers around his spike and giving it a squeeze.   
  
Sideswipe moaned, his hips bucking into Sunstreaker’s mouth. The flow stopped and his spike fully pressurized in a snap, rubbing over Sunstreaker’s glossa. His spike throbbed, his valve clutching hungrily, desperately. Sideswipe rattled, charge bleeding out from beneath his armor, his hands clawing at the wall.   
  
He said something, an unintelligible blurt of words, his hips thrusting his spike deeper and deeper into Sunstreaker’s intake. Pre-fluid trickled freely, coating Sunstreaker’s glossa. Sideswipe’s engine revved, reaching a pitch Sunstreaker knew all too well, as he all but used Sunstreaker’s mouth for his own pleasure.   
  
Sunstreaker stripped his own spike harder, jerking himself with a reckless abandon. Pleasure gathered in his belly, coiling and coiling into a tight knot of need. It clawed toward his array on volcanic fingers.   
  
Above him, Sideswipe abruptly shouted, curling over Sunstreaker’s head as he overloaded, spurt after spurt of transfluid jetting against the back of Sunstreaker’s intake. It joined the mess in his mouth, in his tank.   
  
Sunstreaker spat nothing but static as the overload grabbed hold, and tossed him into a storm of lightning. Pleasure spat out of his spike rapid-fire, transfluid striping the floor and Sideswipe’s feet, and even the wall behind him. His feet tingled. His spark thrashed in his casing. His vents roared, cooling fans screeching.   
  
And then Sideswipe was shoving him off his spike, ever sensitive in the wake of overload, and all Sunstreaker could do was pull off and lean his forehead on Sideswipe’s hip. He panted for ventilation, his world spinning around him, the stench of wastefluid on him, around him, within him.   
  
Primus save him.   
  
He couldn’t bring himself to look up. His hands, both of them sticky with lubricant and transfluid, rested on Sideswipe’s hips. He didn’t dare twitch them. He didn’t want to be noticed. He wondered if he didn’t look up, he could melt away right here.   
  
What if he looked up and there was nothing but disgust? Saying he was okay with something, and then actually doing it, seeing it? Those were world’s apart. Right now, Sunstreaker was filthy. Disgusting. Dirty. He knew it.   
  
Sideswipe shivered again. A ripple passed through his armor. A hand pawed at Sunstreaker’s head. He ignored it until he couldn’t, when fingers curled under his head vent and tugged.   
  
Sunstreaker hissed as he shoved himself to his feet, Sideswipe’s grip unrelenting. He even tried to pull Sunstreaker into a kiss, his other hand hooking around Sunstreaker’s waist and tugging him close.   
  
Sunstreaker turned away as best he could, painfully aware of the mess on his face, sticky and drying and odious.   
  
“Sides, I’ve got--”  
  
“I don’t care!” Sideswipe insisted, cutting off his protest.   
  
He tugged on Sunstreaker’s head vent again, pulling him into a kiss. Sunstreaker made a muffled sound, his spark throbbing with surprise. The kiss was brief, just a brush of their lips, a flick of Sideswipes’ glossa, but it was a kiss nonetheless.   
  
Sunstreaker sagged with relief, easing into Sideswipe’s embrace.   
  
His brother pulled back and made a face, wriggling his jaw. “Okay, so that’s probably not going to be my thing,” he said, twitching his nasal ridge.   
  
Despite himself, Sunstreaker barked a static-filled laugh. “I didn’t say I liked the taste, moron,” he retorted, rolling his optics.   
  
Sideswipe’s thumb swept over Sunstreaker’s head vents. “Well, it’s not like I know what you like about it, sheesh.” His lips curved into a soft smile.   
  
Behind them, the door panel gave a confirming beep and blat, the distinct noises of someone overriding the lock.   
  
What the frag!? 


	4. The Second Round

**Summary for the Chapter:**

> In which Ratchet joins in, and Sunstreaker drowns in their love for him.

Sunstreaker froze, mortification creeping in, as Sideswipe tilted his head, gaze sliding past Sunstreaker.   
  
The door slid open to the sound of footsteps before it closed again. “I knew it,” came a very familiar voice as the panel beeped an override code of confirmation.   
  
It was only Ratchet.   
  
Sunstreaker sagged out of relief, except that the anxiety came back again. It was only Ratchet, but also, here he was, coated in Sideswipe’s waste fluid and standing in a puddle of it.   
  
“Did I not tell you to wait?” Ratchet continued, accusation thick in his tone.   
  
“I must have missed it,” Sideswipe retorted as Sunstreaker looked over his shoulder, well aware of his current state.   
  
Ratchet’s hands were on his hips as he gave Sideswipe a chastising look. Sunstreaker’s fingers tightened on Sideswipe’s hips.   
  
“You’re just mad cause you missed all the fun,” Sideswipe said and his hand shifted to Sunstreaker’s head, fingers stroking the crest of it. “ _Right_?”  
  
Ratchet’s gaze dropped to Sunstreaker and something in it softened. “Right,” he grunted and dropped his hands. “We did have a plan, you know,” he said. “To make sure there weren’t any misunderstandings.”   
  
“Who needs a plan? I say spontaneity is key!” Sideswipe replied cheerfully.   
  
Ratchet glared at him.   
  
“You, um, you actually wanted to be here?” Sunstreaker asked, and hated how small his voice was.   
  
A part of him always knew Sideswipe would never look at him with disgust. Sideswipe was his twin, spark of his spark, the other half of his existence. Sunstreaker had always known his fear of Sideswipe turning on him had been irrational.   
  
But Ratchet wasn’t his twin. Ratchet still got annoyed with their shenanigans. Sunstreaker didn’t want to lose Ratchet’s respect, and he knew, he couldn’t keep this a secret from Ratchet if he told Sideswipe. So he told neither of them.   
  
Now, he didn’t know if he dared meet Ratchet’s optics.   
  
“Yes, I did,” Ratchet said as he approached them. “Mostly to make sure your idiot brother didn’t put his foot in his mouth, but also because I actually have experience in this sort of thing.”   
  
Sunstreaker’s optics widened. “Wait. What?”   
  
“They didn’t call him the Party Ambulance for no reason.” Sideswipe snickered.   
  
“Hush, you.” Ratchet reached for his face as Sunstreaker turned, and red fingers traced the curve of Sunstreaker’s head, through the sticky mess Sideswipe had left on his plating. “Though yes, I have done this before. With a prior partner.”   
  
Sunstreaker frowned, his engine revving. “Who?” he demanded.   
  
Ratchet bopped him on the nasal ridge. “Enough of that now,” he said, much to Sideswipe’s amused delight. “That was a long time ago, arguably before you two were even sparked.”   
  
“We’re not that young,” Sunstreaker muttered.   
  
“Maybe he’s just that old,” Sideswipe said.   
  
Ratchet didn’t rise to the bait. Instead, he curled an arm around Sunstreaker’s waist, his hand flattening against Sunstreaker’s ventrum where he was still damp. Sunstreaker leaned back into his embrace, and shivered as Ratchet’s hand slid further down, fingers encircling Sunstreaker’s half-pressurized spike and giving it a squeeze.   
  
“I know that one overload wasn’t enough to clear your system,” Ratchet said as he started to slowly stroke Sunstreaker’s spike. “Do you want another?”   
  
Sunstreaker licked his lips, and moaned as the taste of Sideswipe’s waste still painted them. “I, uh, I should probably rinse off first.” His hand clamped on Ratchet’s arm, even as he rolled his hips into Ratchet’s grip.   
  
Hands found his hips – Sideswipe’s hands – and they slid upward, drawing a line of charge as they did so.   
  
“What’s the point?” Sideswipe asked cheekily. “You’re just going to get dirty again. I mean, I’m empty, but I’m betting Ratchet’s not.” He leaned in close, pressing their foreheads together. “Wanna play some more?”   
  
Sunstreaker shuddered between them. “Am I dreaming?”   
  
“Nope. We just love ya.” Sideswipe pressed another kiss to the tip of Sunstreaker’s nasal ridge and drew back.   
  
“Indeed,” Ratchet murmured, his fingers wreaking steady havoc on Sunstreaker’s spike, drawing lines of charge with every stroke, ending with a pinch to the tip and a tease to his channel opening. “And my tank capacity is larger than yours.”   
  
Sunstreaker shuddered again. His field flushed with arousal. His spike throbbed, his valve cycled restlessly until several beads of lubricant slipped free. He leaned back into Ratchet’s embrace.   
  
“O-okay,” he said, and felt he should be embarrassed for stammering, but it was all so overwhelming. He’d started the day thinking it was going to be business as usual. He’d never imagined halfway through it that Sideswipe would confront him with his deepest kink and offer to indulge in it. “What, um, what are we going to do?”   
  
“Well, my tank is full and I’m quite sure yours could use some emptying, but just in case, drink this.” Ratchet’s free hand appeared in Sunstreaker’s peripheral vision, holding a cube of something.   
  
It was a teal-ish color, which meant it was neither energon nor coolant. Sunstreaker suspected it was the accelerant that Sideswipe had spoken of earlier.   
  
Sunstreaker accepted the cube and gave it a sniff. It was sweet, almost obscenely so, and the first sip was thick and cloying. It was syrupy.   
  
He made a face.   
  
Sideswipe chuckled. “You’ll grimace at that stuff but not, you know, the other stuff?” He made a vague gesture.   
  
“I never said I liked the taste!” Sunstreaker snapped, or repeated rather. Primus, but Sideswipe was annoying sometimes. “It’s not about that.”   
  
“I know.” Ratchet’s hand dropped to Sunstreaker’s ventrum, stroking the armor there, while his other continued to squeeze and stroke Sunstreaker’s spike. “Ignore him. He’s having a little trouble understanding. Drink the cube.”   
  
Sunstreaker snorted, but obeyed, sucking it down as quickly as possible so as not to linger. “Yeah, well, I didn’t understand why he wanted us to rape him either, but I didn’t tease him about it.”   
  
“Hey!” Sideswipe reared back, indignant.   
  
“Children,” Ratchet said warningly, but it was a hint of amusement. “If you can’t play nicely, then we won’t play at all.”   
  
Sunstreaker swallowed down the last of the cube and shuddered. He dispersed the energy field with a flick of his fingers as another shudder wracked his frame. The low-key arousal in his groin simmered quite nicely with Ratchet’s slow, but determined pace. He could sit like this for hours, with Ratchet humming behind him, and just working his spike. It was kind of nice to slow-build toward overload.   
  
“We’re going to find out your secret kink eventually, Ratchet,” Sideswipe said, a blatant change of subject if Sunstreaker ever heard of. “Just you wait.”   
  
Ratchet snorted. “I have no secrets, but feel free to keep looking.” He patted Sunstreaker’s ventrum again. “Give that about ten minutes to do its work and then we can get down to business.”   
  
Sunstreaker’s backstrut curved, his ventilations stuttering. “You… you have something in mind?” he asked, his fingers tightening where they gripped Ratchet’s arm. Lubricant dripped steadily from his valve now.   
  
“Mmm. I do.” Ratchet’s hand stroked down to the base of Sunstreaker’s spike, and then his middle finger flicked Sunstreaker’s primary anterior node, making him squirm. “You’ll be feeling full soon. You’ll need somewhere to release all that pressure, won’t you?” His finger flicked again.   
  
Sunstreaker moaned, his optics shuttering. “Are you… volunteering?”  
  
“I am.” Ratchet nibbled on the corner of Sunstreaker’s right head vent, the one he belatedly noticed had been spared a soaking. “Or at least my valve is. My indulgence only goes so far.”   
  
Sunstreaker’s cheeks heated. “Fair enough,” he said, and licked his lips again.   
  
“What about me?” Sideswipe demanded with his lower lip jutted out. He crossed his arms over his chestplate. “I’m feeling left out over here.”   
  
Ratchet huffed a ventilation. “We indulge you all the time, greedy.”   
  
“You and your ten thousand ideas,” Sunstreaker added and shivered again as Ratchet’s fingers abandoned his spike entirely, stroking instead around the rim of his valve. They traced every one of his secondary sensors.   
  
Ratchet’s other arm curved around Sunstreaker’s torso, flattening against his chestplate. He didn’t seem to mind the smears of Sideswipe’s wastefluid. “He’ll get his. Maybe. It depends. You want me on my back or my knees, Sunny?”   
  
Somehow, he didn’t mind so much when Ratchet called him ‘Sunny’.  
  
“I want to see your face,” Sunstreaker said without any hesitation.   
  
Sideswipe grinned like a mech who had a secret. “You should make him ride you then. Cause what Ratchet’s not saying yet, is that he doesn’t use his spike.”   
  
Sunstreaker blinked, rising from the haze of pleasure he’d been slowly sinking into. A pressure built in his abdomen as well, there on the left hand side, where his waste storage tank was located. He was weeks away from needing to drain, but all of the sudden, that distance felt more like hours.   
  
“What?”   
  
Ratchet made an aggravated noise. “You are a pain in my aft,” he grumbled. “Yes, I don’t use my spike. I drain through my valve.”   
  
Sunstreaker blinked again. His processor supplied him images without any further prompting. His engine revved.   
  
Ratchet. Riding him. Releasing the waste so that it painted Sunstreaker’s array and mingled with lubricant and transfluid. It would be so dirty, so messy.   
  
The moan rose up in his intake before he could stop it. His spike throbbed, valve cycling hungrily.   
  
“Ride me,” Sunstreaker said as he rolled his hips into Ratchet’s touch, frotting his valve against Ratchet’s fingers. “I want you to ride me.”   
  
“Then I will,” Ratchet purred into his audial. His hand shifted to Sunstreaker’s side, pressing in on his plating over his increasingly uncomfortable tank. “You feel it yet?”   
  
His knees started to shake. “Yeah.”   
  
Ratchet pressed a little harder, until the alert popped up in Sunstreaker’s HUD. The need to drain turned into a requirement, yet his arousal remained strong. His spike steadily leaked pre-fluid, his spark spinning faster and faster.   
  
“Better hold it in, Sunny,” Ratchet murmured, his fingers slipping between Sunstreaker’s armor plates and kneading, applying a direct pressure to Sunstreaker’s full tank. “Wouldn’t want to make a mess, would you?”   
  
A strangled sound escaped Sunstreaker’s intake. His knees wobbled, and he gripped at Ratchet all the harder.   
  
“Wow, this really amps your charge, doesn’t it?” Sideswipe murmured, sounding awed rather than teasing this time.   
  
“We all have our kinks.” Ratchet stroked around the rim of Sunstreaker’s valve again, painting the sensors with Sunstreaker’s own lubricant. “Now why don’t you lay down so I can ride this, hmm?” His fingers returned to Sunstreaker’s spike, giving it a squeeze in demonstration.   
  
A moan eked from Sunstreaker’s vocalizer. “Okay,” he said, and he knew he sounded dazed. He felt it. Arousal and affection swarmed together, crowding his spark. Part of him remained stunned that his brother and their mate would both be willing to indulge him in this dirty, dirty secret.   
  
Another press of Ratchet’s fingers and Sunstreaker’s tank throbbed. The urge to relieve the pressure came over him in a wave. Holding back was a struggle that left him gasping, just shy of pain, and that sent another wave of arousal through his systems. Lubricant leaked steadily from his valve now.   
  
“You might wanna help him down, Ratch. He’s pretty gone,” Sunstreaker heard Sideswipe say, though as if from a distance.   
  
Sunstreaker worked his intake, moaning again. Ratchet said something in response, but it was a roar and rush of words. And then he felt the cool tiling of the washrack beneath his back. It was slick behind his head, the odor of Sideswipe’s earlier release of waste floating up from beneath him.   
  
It was not a pleasant odor, bitter and cloying, but it was a reminder of what Sideswipe had done for him. Sunstreaker groaned and roughly fisted his spike.   
  
“Enough of that now. That’s for me,” Ratchet said, and his fingers flicked at Sunstreaker’s.  
  
He forced his optics to unshutter, unable to remember when he’d shuttered them, and was greeted to the sight of Ratchet straddling his thighs. The medic’s spike had yet to emerge, but his valve panel had slid aside, revealing the dewy wetness of his array. Lubricant glistened in the shadows.   
  
Sunstreaker’s mouth filled with lubricant. He couldn’t decide if he wanted Ratchet to ride his spike or his face. He licked his lips and squeezed his spike harder.   
  
Sideswipe snickered from somewhere above Sunstreaker. “He can’t decide what he wants, Ratch.”   
  
“Then I’ll have to decide for him,” Ratchet said, and flicked Sunstreaker’s spike again. “Come on, Sunny. Let go.” One hand landed on Sunstreaker’s abdomen, palpating his armor and sliding into the seams to press against his over-full tank. He scooted forward, until Sunstreaker’s spike was shadowed by the vee of his thighs.   
  
Sunstreaker groaned, his free hand grabbing Ratchet’s about the wrist and making him press harder. “I want… I want...”   
  
“I know what you want,” Ratchet said, fingers rubbing and rubbing until Sunstreaker felt as though he would burst. “This isn’t a one-time deal, Sunny. I’ll indulge you again if you want.”   
  
“What about me?” Sideswipe demanded, and Sunstreaker didn’t have to look to know he was pouting.   
  
“We’ll get to you, brat,” Ratchet said, rolling his optics. “You can pick later.”   
  
Susntreaker’s hips bucked, his spike sliding along the inside of Ratchet’s thigh, ghosting all too near the wet heat wafting from Ratchet’s valve. “You… spoil him,” he gasped out, fingers tightening around Ratchet’s wrist.   
  
“I spoil you both,” Ratchet corrected, and two fingers pressed deep, the tips of them like a spear prodding at Sunstreaker’s tank.   
  
His hips bucked. His belly throbbed. A shudder wracked Sunstreaker’s frame as he struggled to keep himself back, his vision briefly whiting out. It hurt, but the pain was so distant to the anticipation.   
  
Sunstreaker moaned, his free hand clawing at the tile, landing in a sticky wet spot that he just knew had to be leftover from Sideswipe. He shuddered, spark throbbing, spike pulsing where it rubbed again and again at Ratchet’s thigh.   
  
“Ratchet,” he whimpered, not even sure what he wanted. If he wanted Ratchet to press harder, or sink down on his spike, or both.   
  
“I know.” Ratchet’s hips dipped just enough that the head of Sunstreaker’s spike nudged at his damp rim, tasting the lubricant that dripped onto his transfluid slit.  
  
Ratchet’s fingers added pressure again, rubbing firmly against Sunstreaker’s protoform, nudging the tank beneath. Sunstreaker’s back arched, his legs trembling from the overwhelming need to just let go, release it all.   
  
“It’s okay, Sunny,” Ratchet murmured, his free hand grabbing Sunstreaker’s jaw and forcing their gazes to meet. There was nothing in his optics but encouragement. “Let go.”   
  
Sunstreaker’s engine whined. His hand clawed the floor, the other tightening around Ratchet’s wrist. He distantly heard the sound of metal creaking, but it was lost to the rattle that attacked his frame. He gasped as the last vestiges of control vanished, and his wastefluid erupted from his spike.   
  
He heard the sound it made as it splashed up against Ratchet. He felt the scorching heat as it rained back down, pattering on his hips and groin and upper thighs. Sunstreaker’s vents roared as Ratchet abruptly dropped, his valve swallowing Sunstreaker’s spike and the steady stream of wastefluid that emerged from it.   
  
Sunstreaker grabbed for Ratchet, curving forward as he snatched at Ratchet’s hips, holding the medic down on top of him. His feet shoved at the floor, desperate for leverage as he bucked up into Ratchet, his spike firming entirely as the last spurt of wastefluid cleared from his tank. Arousal rushed in the wake of relief, his spike pushing deep, grinding against Ratchet’s ceiling node.   
  
Ratchet hissed, cursed quietly, but his hands grasped onto Sunstreaker’s shoulders.   
  
Everything around Sunstreaker was noise. Static in his audials. Metal impacting metal. The wet, hot squelch of lubricant and wastefluid. The slap of his frame between Ratchet’s thighs and the puddle beneath his aft. The stench of his own waste, so bitter and cloying, and Ratchet was still here, Ratchet’s knees dug into the tile as he worked his hips, riding Sunstreaker’s spike, his valve eagerly clutching at it.   
  
Ratchet was still here, because Ratchet loved him, and Sunstreaker almost sobbed for that reason alone, were it not for the desire that snatched hold of him and refused to let go. Overload clawed at him, rakes of fire deep in his frame, a boiling surge of need that demanded.   
  
Ratchet grabbed his head and yanked him into a kiss. Sunstreaker moaned as Ratchet bit at his lips, hard enough to draw energon, their glossa tangling. There was warmth at his back, the burr of another engine, a hand on his belly, heated ex-vents against his spinal strut.   
  
Ratchet slammed down, valve taking him deep, cycling tight, so tight that their nodes latched together, charge exchanging between them. Sunstreaker whimpered into Ratchet’s mouth, a full-frame tremor taking him over. His spike throbbed, his vents roared, and the pleasure ignited into a supernova.   
  
Sunstreaker bucked, his hands tightening to the tune of dented metal, and his senses whited out as overload stripped him raw, stripped him of all sense of the here and now. Pleasure rattled his frame from head to foot, stole his ventilations, stole his thoughts. He bucked helplessly, spilling into Ratchet’s valve, transfluid joining the mess between them.   
  
He panted orally, slowly coming to himself, realizing that it was Sideswipe at his back, of course it was. Ratchet had pressed their foreheads together, his hands still cupping Sunstreaker’s head. Their arrays were still joined, Ratchet’s valve cycling restlessly, his body trembling on the cusp of overload. Or maybe something else. Ratchet still had a full tank.   
  
“Nnn,” Sunstreaker managed and rebooted his optics, his frame thrumming from the force of the overload.   
  
“You with us?” Ratchet asked, his tone amused, though his voice was husky.   
  
“Primus, that was hot,” Sideswipe said, tucked against Sunstreaker’s back, his spike rutting against his backstrut, leaving streaks of transfluid behind. “We gotta get you to lose control more often.”   
  
Sunstreaker made a noncommittal noise and tried to meet Ratchet’s gaze. “You… didn’t overload?” he slurred.   
  
“No, he didn’t,” Sideswipe said with a laugh. “You owe him one, bro.”   
  
Ratchet huffed. “It’s fine.”   
  
“No, it’s not,” Sunstreaker said, forcing himself to stir. He felt weird, sated, but almost like he were drugged. The world seemed to float around him, and everything about it felt good.   
  
He unpeeled his fingers from Ratchet’s hips, sliding them to Ratchet’s waist. He leaned forward, brushing his lips over the curve of Ratchet’s jaw. “Wanna lick you. Can I?”   
  
Ratchet shivered. His hold on Sunstreaker’s jaw gentled, his valve fluttering around Sunstreaker’s half-pressurized spike. “Course you can, Sunny,” he said, his mouth darting down to briefly catch Sunstreaker’s lips. “I’m all yours.”   
  
A shudder raced over Sunstreaker’s plating. He squeezed Ratchet’s hips as he bit at Ratchet’s lips. “Lay down for me?”   
  
“My pleasure.” Ratchet eased out of hold, sliding back so that he could stretch out across the floor, his knees drawn up and tilted out, his array on display.   
  
Sunstreaker’s wastefluid and transfluid painted his valve rim and seeped in slow dribbles from the interior. Ratchet’s biolights blinked fitfully, his spike standing proud from the apex of his thighs. Sunstreaker’s mouth watered. He worked his intake and rolled to his knees before crawling toward Ratchet, his gaze focused on Ratchet’s swollen folds.   
  
Sunstreaker made a noise deep in his intake as he shimmied to his belly and hooked his arms under Ratchet’s thighs, his hands pinning Ratchet’s hips so that he had nowhere to go. He in-vented, drawing in the mingled scents of Ratchet’s arousal and Sunstreaker’s own fluids.   
  
He moaned, rubbing his cheek against the hot, swollen mesh of Ratchet’s valve rim. Slick fluids coated his dermal plating.   
  
Ratchet’s thighs trembled around him. One hand petted the top of Sunstreaker’s head. “Ah, Primus, that’s good, Sunstreaker.”   
  
The praise went straight to his spark, which fluttered with delight. Sunstreaker’s mouth watered again, his array cycling back to heat.   
  
Hands landed on his aft and hips, stroking them, before they curled around Sunstreaker’s thighs and gave them a squeeze.   
  
“Gonna let me in, bro?” Sideswipe asked, his voice thick with arousal, his hands warm where they stroked Sunstreaker’s seams.   
  
His spark pulsed an affirmative at Sideswipe, who pulled him up, pushing Sunstreaker’s lower half to his knees so that Sideswipe could notch between them. His fingers stroked over Sunstreaker’s dripping valve, teasing the ring of exterior nodes and setting a new blaze to life in Sunstreaker’s array.   
  
Sunstreaker moaned as he turned his face toward the depths of Ratchet’s valve and gave it a long, deep lick, gathering a taste of the sticky mess. Ratchet hissed a ventilation, bucking up against his mouth, his main node pulsing. It called to Sunstreaker, and so he moved to greet it, giving it a flick of his glossa before sealing his lips around it.   
  
Ratchet moaned, his legs trembling where Sunstreaker gripped them, his feet pushing against the floor. His engine rumbled. His valve pulsed against Sunstreaker’s lips, pushing out more lubricant, and more of Sunstreaker’s own mess in the process.   
  
Primus.   
  
Sunstreaker panted against Ratchet’s valve, giving it long, and savoring licks. He tasted every fold, every sensor, coming back to the main nub again and again. He shifted his right hand to pat over Ratchet’s lower half, wondering where Ratchet’s tank could be found and whether he felt the pressure of it, too.   
  
“Don’t forget, bro,” Sideswipe said, his hips rocking against Sunstreaker’s aft, his spikehead teasingly scraping over Sunstreaker’s rim and folds. Each sweep of his spike through the lubricant made Sunstreaker shudder.   
  
The two of them were going to drive him mad.   
  
“Ratchet’s still nice and full for you,” Sideswipe said.   
  
Sunstreaker’s ventilations caught. His hands tightened on Ratchet as he shoved his face into the medic’s valve, his mouth and nasal ridge eclipsed by the scent and taste of him.   
  
Sideswipe groaned, his hands squeezing around Sunstreaker’s aft, before the tip of his spike found Sunstreaker’s valve and filled him in one, deep push. Sunstreaker shuddered, his valve cinching down, finally full.   
  
Sideswipe set up a rhythm, slow and deep, his spike cleaving a path of pleasure, grinding Sunstreaker’s internal nodes one by one.   
  
Full. Still full. Could drench him in it. Could bury him in it. Surrounded by his mates, his lovers, completely safe and desired.   
  
Sunstreaker moaned against Ratchet’s plump, swollen valve. He nuzzled it with lips and glossa and nasal ridge, seeking out Ratchet’s main node again and latching on to it. He flicked it with his glossa, again and again, and held Ratchet as his hips jerked with each flick.   
  
Ratchet’s engine roared. His thighs tensed and shook. More lubricant trickled free, his node throbbing against Sunstreaker’s lips. He was close, so close, and Sunstreaker wanted to taste him going over.   
  
Hands scrabbled at Sunstreaker’s head, pressing him down, keeping him close. Ratchet’s backstrut arched, his feet thumping a pattern across Sunstreaker’s upper back. He loosed a choked cry.   
  
Close. So close.   
  
Sunstreaker hummed, suckling on Ratchet’s main node, and was rewarded with a sharp gasp. Ratchet bucked beneath him, hands tightening, and then he overloaded, rutting hard against Sunstreaker’s mouth as his valve pulsed. His thighs squeezed around Sunstreaker’s head, catching on his head vents with a screech of metal on metal.   
  
Sunstreaker nuzzled his valve, drawing out the tremors of overload, lapping up every trickle of lubricant as it squeezed out of Ratchet’s valve. The grip on his head eased and Sunstreaker lifted his head enough so his lips could brush over Ratchet’s depressurizing spike. Dual-overload, hm? Well, that explained the damp feeling on the back of Sunstreaker’s neck and head.   
  
“That looked like a good one,” Sideswipe said, his spike throbbing in Sunstreaker’s valve. He’d stopped thrusting sometime before Ratchet’s overload, but now he began again in earnest, rolling his hips with each thrust so that he ground against Sunstreaker’s ceiling node.   
  
Ratchet’s vocalizer spat static before he rebooted it. His engine rumbled. “It was. Thank you, Sunny.”   
  
“Mm, my pleasure.” Sunstreaker returned his attention to Ratchet’s valve, pressing light kisses to his rim. “Can I have it now?”   
  
Sideswipe chuckled, though it didn’t sound taunting. His hips rocked against Sunstreaker’s aft as he pressed deep and circled them, grinding over every one of Sunstreaker’s internal nodes.   
  
“You know what he wants, Ratchet,” Sideswipe said, his fingers flexing where they gripped Sunstreaker’s hips.   
  
Ratchet propped himself up on his elbows, looking over the rise of his windshield at Sunstreaker between his thighs. “Yeah, I do,” he said.   
  
Sunstreaker looked up at him, saw nothing but affection glowing in Ratchet’s optics. A red hand pet the top of his head and curved around it, stroking him.   
  
“You ready?” Ratchet asked.   
  
Sunstreaker quivered. His valve spun tight, locking around Sideswipe’s spike, forcing a groan out of his brother.   
  
“He’s definitely ready,” Sideswipe gasped, his ex-vents teasing over Sunstreaker’s aft and back. He must have leaned forward.   
  
“Please,” Sunstreaker murmured, his lips brushing over Ratchet’s exterior node, making Ratchet twitch. He jerked forward, Sideswipe thrusting into him a bit harder, but it was hard to focus on that pleasure while he danced on the cusp of anticipation.   
  
Ratchet’s gaze softened. His hand caressed Sunstreaker’s head again. “All right,” he said. “Here it comes.”   
  
Sunstreaker’s gaze dropped; his spark pounded. Ratchet’s thighs eased around his head as some of the tension in Ratchet’s frame went away. He pulled back a fraction, his gaze locked on Ratchet’s valve as the first trickles of wastefluid started to emerge, oily and pungent.   
  
Sunstreaker worked his intake, trapping a moan in his vocalizer. The stream increased in volume, gushing from Ratchet’s valve, joining the mess of lubricant beneath Ratchet’s aft. It was differently colored than Sideswipe’s, and thinner, too. It smelled less metallic, weaker for that.   
  
The puddle beneath Ratchet’s aft grew larger. Ratchet sighed a soft sound of satisfaction, and Sunstreaker looked up at him, but still, there was nothing in Ratchet’s expression but affection.   
  
It didn’t matter at all, did it? It didn’t matter at all.   
  
The flow eased back to a trickle. Sunstreaker licked his lips. He couldn’t let the rest go to waste.   
  
He pressed his mouth back to Ratchet’s valve, licking a long line up the center of it, flicking the tip of his glossa over Ratchet’s anterior node. Ratchet shivered, and then groaned when Sunstreaker sealed his lips over Ratchet’s valve, sliding his glossa inside. Ratchet’s wastefluid trickled over his glossa, into his mouth, across his glossa, down his intake.   
  
The taste wasn’t as strong as Sideswipe’s, but still bitter. It was even more oily, clinging to every surface of his mouth. It trickled down his intake, into his tanks. Sunstreaker moaned as he swept his glossa around the inside of Ratchet’s valve, seeking out the aperture from which Ratchet eliminated his waste.   
  
He found it just as Ratchet’s flow ceased, only a few more drops emerging. Sunstreaker shivered as he licked into Ratchet’s valve, glossa seeking out that slit and adding a nice pressure to it.   
  
Ratchet moaned and bucked against him, his hand curving around the back of Sunstreaker’s head. His valve throbbed against Sunstreaker’s lips, stuttered ventilations indicating he’d never truly cycled down from overload. Not as Sunstreaker heard the slick sounds of him fisting his spike with his free hand.   
  
Sunstreaker’s ventilations crackled. He gripped harder onto Ratchet, burying his face in Ratchet’s valve, surrounding himself with the familiar taste and scent, Ratchet’s wastefluid strong on his glossa. But more than that was the absolute love in Ratchet’s field. The acceptance. The way both he and Sideswipe still embraced Sunstreaker, touching him as though he mattered.   
  
Sunstreaker whimpered, rubbing his face over Ratchet’s valve, his own rippling around Sideswipe’s spike as his brother pushing into him faster and faster. As one of Sideswipe’s hands slid around Sunstreaker’s body, his fingers finding Sunstreaker’s spike and working it nicely.   
  
Sunstreaker panted, his world narrowing down to this. To the smell and taste of Ratchet in front of him, and Ratchet gasping and moving beneath him. To the feel of Sideswipe thrusting into him, faster and deeper, raking along his internal nodes. Their fields surrounding him, embracing him, thick with desire and acceptance.   
  
Sunstreaker’s entire frame shook. His spark throbbed. Pleasure lanced through his systems like a lightning bolt, one that started in his belly and seemed to radiate outward. He clutched at Ratchet, holding tight, as the overload snatched hold and tossed him about, his frame spasming in the grips of ecstasy.   
  
He felt, distantly, the hot splash of Sideswipe’s transfluid along his valve lining, spattering over sensitized nodes, and that only prolonged the pleasure. Sunstreaker’s hips bucked, his frame shaking, as beneath him, Ratchet shattered. More fluid spattered Sunstreaker’s head as Ratchet’s spike spurted.   
  
Sunstreaker moaned, his voice striped in static. He gentled his hold on Ratchet, tilting his head to rest his forehead against Ratchet’s inner thigh, panting for ventilations. Little tremors raced through his frame as his cooling fans spun mightily, struggling to draw cooler air into his systems.   
  
Ratchet’s hand returned to his head, petting him in short, smooth strokes. His fingers shook, his field heavy with satisfaction.   
  
Heat across Sunstreaker’s back clued him in to Sideswipe, whose spark Sunstreaker could feel whirling madly. Sunstreaker’s own spark throbbed in response, a quiet hello through the armor that separated them. Sideswipe’s spike lingered in Sunstreaker’s valve, half-pressurized but present.   
  
Sunstreaker’s optics shuttered. His frame thrummed. Had that really happened? He still wasn’t sure if he dared believe it.   
  
“Sunstreaker? You with us?” Ratchet asked.   
  
“Mmmm.” He forced his optics to online, blinking as he looked up at Ratchet. “’M with you,” he replied.   
  
“He’s pleasure-drunk is what he is,” Sideswipe said with a chuckle. One hand slid up from where it pressed against Sunstreaker’s belly, to stroke over Sunstreaker’s chestplate above his spark. “We blissed him out. He must really like this.”   
  
“Nnn. That’s not it,” Sunstreaker said, struggling to coherency. He unwound his arms from Ratchet and struggled to push himself up, though his limbs felt like jelly. “It’s not about the… the waste, Sides.”   
  
Ratchet’s hand curled under Sunstreaker’s chin, tilting his head up to look into Ratchet’s optics. “It’s about trust, isn’t it?” he asked quietly.   
  
Sunstreaker leaned into Ratchet’s hand. “You said yes,” he replied barely above a whisper as Sideswipe’s arms wrapped around him, embracing him from behind. “You still love me.”   
  
Ratchet curled toward him, pressing their foreheads together. “Yes, Sunstreaker. I still love you.”   
  
“And you know that I do,” Sideswipe added, giving Sunstreaker a squeeze and nuzzling the back of his head. “I’ll always love you. No matter what.”   
  
There it was. The thing he knew all along, but sometimes, didn’t dare to trust. Sunstreaker trembled between them, his spark throbbing with warmth, with acceptance. He wondered if he could stay in this moment forever, trapped in time, and never again face what was out there.   
  
He knew he couldn’t. He just wished he could.   
  
“Sunny,” Sideswipe said, his hand stroking Sunstreaker’s chestplate. “I really do love you, but is it okay if we get clean now?”   
  
Ratchet laughed. Even Sunstreaker managed a chuckle. He wriggled out of the tight embrace, despite wanting to linger there forever.   
  
“Yeah,” he said. “Let’s get clean.”   
  
Sideswipe grinned and pumped a fist into the air. “I’ve never wanted a shower so badly,” he said as he danced over to the sprayer, twisting it onto his preferred setting. “Except maybe that one time Prowl punished us by giving us a scouting assignment in the desert. Sand. So much sand.” He shuddered, his plating twitching.   
  
Ratchet and Sunstreaker exchanged glances from where they sat on the floor, still in a puddle of sticky fluids.   
  
“You know, we did neglect him a little,” Ratchet said, a devious smile pulling at his lips.   
  
Sunstreaker’s gaze wandered from Sideswipe, to the spray of solvent, and back again. “We did,” he agreed, giving Ratchet a conspiratorial look. “And I think he needs a hand or two getting clean, don’t you?” He stood up, his gaze focused on his oblivious twin.   
  
Ratchet chuckled. “He does tend to miss a few spots.” He climbed to his feet, making a show of dusting off his frame. “Together?”   
  
Sunstreaker nodded. “Together.”   
  
They pounced.   
  



	5. Washing Up

**Summary for the Chapter:**

> Sideswipe would do anything for his brother, but he still wanted to get clean as soon as possible.

It took all Sideswipe possessed to hide how grossed out he was.   
  
Not with Sunstreaker. No, never with Sunstreaker. But the room smelled of waste, and while most of it was on Sunny, a bit was on Ratchet, and the rest was on Sideswipe, and he didn’t like it. Not one bit.   
  
His palm smacked the washrack controls, lukewarm solvent spattering his chestplate as a result. Sideswipe swallowed down a sigh of relief as the almost flowery scent of the cleanser started to chase away that of the pungent waste.   
  
He really, sincerely hoped this was one of those kinks Sunstreaker wanted rarely, rather than a daily, weekly or frag, even monthly.   
  
Please.   
  
Sideswipe tilted his face under the solvent spray and let it streak down his faceplate, his intake, and beneath the surface of his armor. He hummed as it started to wash away the sticky residue of waste. At this point, he didn’t even know who it belonged to anymore.   
  
Did it honestly matter?   
  
“You look like you could use some help.”   
  
“Mind if we lend a hand?”   
  
That was all the warning Sideswipe had before hands descended on him, pulling him out of the solvent spray. His back hit a very warm, voluptuous bumper – had to be Ratchet – even as Sunstreaker stepped between him and the solvent spray.   
  
“Aw, I wanna get clean,” Sideswipe said, trying for his most winning pout. He hoped none of his disgust showed on his face.   
  
Sunstreaker grinned at him, the corner of his mouth curving into a devilish smirk that did things to Sideswipe’s spark. “And we just want to help,” he purred as he reached up to detach the sprayer from the hook.   
  
One of Ratchet’s hands splayed over Sideswipe’s belly, tugging him more firmly into Ratchet’s embrace. “You’re pretty filthy,” Ratchet murmured into his audial, ex-vents ghosting across it. His hand slid further down, fingers seeking the tip of Sideswipe’s depressurized spike. “We could help.”   
  
Sideswipe shivered. His glossa swept over his lips. There was promise in Ratchet’s voice, enough to help shove aside the lingering distaste.   
  
Sunstreaker detached the sprayer and flicked his thumb over the switch, shifting the head to something with a firmer spray. That roguish curve to his lips only widened as he turned toward Sideswipe with predatory intent.   
  
Steam filled the space between them.   
  
“Okay,” Sideswipe said, and flashed his twin his most charming grin. “Since you’re both so insistent and all.”   
  
Ratchet chuckled. “We can be, given enough incentive.”   
  
His other hand crept around Sideswipe’s midsection and slid down, ghosting past his awakening spike to Sideswipe’s uncovered valve. Talented medic fingers circled his anterior node before dipping lower, slipping a single digit into Sideswipe’s valve.   
  
His backstrut arched. He leaned hard against Ratchet, array tingling.   
  
“Better?” Ratchet asked.   
  
“Much,” Sideswipe sighed.  
  
Even more so when he felt the warm patter of solvent back against his frame. It splashed against his chestplate before moving down, cleanser draining in rivulets down his armor.   
  
The spray continued on, but it skipped over his array and focused on his thighs and legs, rinsing both clear of the varied fluids spattered on them. Ratchet’s hands continued to tease, tugging on his spike, slowly fingering him.   
  
The smell of cleanser gradually replaced that of waste, until Sideswipe’s vents pulled in nothing but the solvent and his own growing need. It was much, much better, and he quickly found himself relaxing in Ratchet’s embrace, his knees growing wobbly.   
  
The solvent spray abandoned him, and Sideswipe shivered as cool air seeped in where the cleanser had been. But that didn’t last long as Sunstreaker cupped his jaw and nuzzled him, his faceplate dripping with solvent, and smelling only of Sunstreaker.   
  
Ah. Perfect. See. This was why he loved his twin.   
  
Sideswipe nuzzled back, his lips seeking out a kiss that Sunstreaker kept avoiding. Sideswipe pouted.   
  
“Kiss me,” he said, his hands grasping at his brother’s hips and waist, trying to tug him closer.   
  
“No. I’m still gross,” Sunstreaker said, but it was with a warm laugh. He brushed their nasal ridges together. “Kiss Ratchet instead.”   
  
Mmm. That didn’t sound half-bad.   
  
Sunstreaker turned his head to the side, toward Ratchet behind him, and Sideswipe purred as Ratchet’s lips brushed his. Ratchet’s glossa flicked out, teasing the seam of his lips. Sideswipe sighed into the kiss.   
  
Ratchet tasted like mid-grade and energon goodies. Ooo, but someone had been sneaking treats on the clock again.   
  
Sideswipe loved the mental image of Ratchet bent over his desk, working on paperwork, one hand sneaking into that side drawer where he kept a bin of goodies. The messy ones that weren’t good for you at all.   
  
Ratchet slid a second finger into Sideswipe’s valve, curling them just right to tap over a node cluster, and Sideswipe shivered. He moaned into the kiss, hips rolling into Ratchet’s fingers, as the warm solvent pattered over his frame again.   
  
Sunstreaker’s thumb swept over his cheek lovingly. His field stroked Sideswipe’s, blooming with affection and gratitude.   
  
Ratchet rubbed their nasal ridges together. He squeezed Sideswipe’s spike. “What say you sit down, hm?”   
  
“Old mech,” Sideswipe teased, though he had to admit, his knees were wobbling. “Can’t stand for too long.”   
  
“Something like that.” Ratchet pecked him on the lips again before he started to sink, drawing Sideswipe down with him. “You just stay where I want you.”   
  
“Mmm. Don’t have to tell me twice.”   
  
Ratchet sank to his knees and pulled Sideswipe into his lap, his back pressed to Ratchet’s chestplate. His thighs splayed wide over Ratchet’s, his entire array on display, with one of Ratchet’s arms encircling his waist. The other draped across his right thigh so that Ratchet’s hand could continue to squeeze and stroke his spike.   
  
Sideswipe reached up and back, hooking his hands together behind Ratchet’s neck. He knew it was the right choice when Sunstreaker looked down at them, optics dark and heated.   
  
Sideswipe grinned. Yep. He didn’t need wasteplay to attract his twin. He was a sexy Lamborghini all on his own. Especially spread out like this, all of him on inviting display, his limbs stretched, his transformations seams gaping, his cables shining beneath.   
  
The solvent spray returned, hitting the inside of his thigh, close enough he could feel the drizzle of it against his valve folds. Sideswipe shivered again, arching back against Ratchet. He looked up at his twin, Sunstreaker staring back at him with concentration and desire in his optics. His glossa flicked over his lips, his fingers firmly wrapped around the showerhead.   
  
“Gonna help me get clean?” Sideswipe challenged, artfully arching his backstrut. His thighs trembled where they braced over Ratchet’s.   
  
Ratchet snorted a laugh. “You’re absolutely ridiculous,” he said, but his hand kept stroking Sideswipe’s spike anyway. He used long, squeezing pulls, root to tip, root to tip, one digit tapping down over Sideswipe’s caudal spike node.   
  
The solvent spray inched closer. The lightest intensity brushed over Sideswipe’s valve, pecking at his anterior node. He rumbled a moan, frame shivering.   
  
“I did make a mess,” Sunstreaker purred as he lowered himself to his knees and shuffled forward, until the showerhead cord stretched taut, and he was bracketed by both Ratchet’s and Sideswipe’s thighs. “I suppose it’s my responsibility to clean it up.”   
  
Sideswipe trembled with anticipation. He sucked in a heavy ventilation, hips canted toward Sunstreaker. Ratchet pressed a kiss against the curve of his jaw, lips tickling as they dipped toward the side of Sideswipe’s intake.   
  
Sunstreaker flicked his thumb, and the solvent stream narrowed, increasing its intensity. It made a dull droning noise as it rained down on Sideswipe’s inner thigh armor. He worked his intake, ventilations stuttering, valve pulsing excitedly, as the spray moved closer.   
  
Closer and closer.   
  
He moaned, optics flickering. He arched harder against Ratchet, his spike throbbing in Ratchet’s fingers.   
  
The shower spray made a pass over his array, briefly splashing against his anterior node before it was gone again. Sideswipe gasped, his thighs trembling. His valve pulsed.   
  
“Sunny!”   
  
“Don’t call me that,” Sunstreaker murmured, but it lacked heat. His gaze was dark and heavy on Sideswipe. “You want it?”   
  
Sideswipe chewed on his bottom lip. “You know I do.”   
  
“Mmm. I’m not sure I believe him,” Ratchet purred as his denta made teasing nips to Sideswipe’s neck cables. “He doesn’t sound desperate enough.” His hand paused on Sideswipe’s spike, holding him firmly, but not stroking him at all.   
  
Sideswipe rattled an ex-vent. “You’re both mean.” He writhed in Ratchet’s hold, trying to twist his frame back toward the spray of the nozzle. It remained tantalizingly out of reach, only the distant drizzle of it touching his valve, where it sizzled upon contact. “And after I played nice and everything.”   
  
Sunstreaker chuckled. “You think that means you deserve a reward?”   
  
“I don’t know. A few minutes of good behavior for once?” Ratchet’s hand gave a long, firm pull, ending with a pinch to the tip of Sideswipe’s spike. His hips jerked. “What do you think that’s worth?”   
  
Sunstreaker’s free hand rested on Sideswipe’s knee, fingers curling around to tickle under the joint. “Maybe just a little,” he murmured.   
  
Sideswipe wheezed. “Please.” He offered his best impression of a Bluestreak plea.   
  
It must have worked. The spray inched back toward his valve.   
  
He whined, canting his hips toward it, ventilations stuttering. Heat splattered against his inner thigh, his hip joint, his valve lip and finally, it roared into his valve opening. Sideswipe whimpered as it splashed up into his valve, all bubbling wet heat washing over his nodes.   
  
Sideswipe’s backstrut arched. His armor creaked as his hips pumped, riding the pressure of the solvent spray, his spike working into Ratchet’s fist.  
  
Primus, it felt fragging amazing. A drumming pressure on his sensitive dermal mesh, a tickling tease to his internal nodes, an arrhythmic brush over his anterior and caudal nubs.   
  
“Oh, please don’t stop,” he begged, hips working, rolling into and over the fierce spray.  
  
Sunstreaker’s hand slid down his thigh, toward Sideswipe’s valve. He tracked it tangentially, caught between the pressure of the solvent and Ratchet’s hand on his spike, now stroking him firmly, squeezing with each upward pull.   
  
The spray angled, striking deeper within Sideswipe. He groaned, his valve clenching down on nothing, calipers fluttering madly. Heat gathered in his array, blossoming into an inferno.   
  
“Now you’re feeling it,” Ratchet growled into his audial. His arm tightened around Sideswipe’s waist. “Gonna overload for us?”   
  
“He damn sure is,” Sunstreaker said fiercely.   
  
Sideswipe nearly shrieked as Sunstreaker’s free hand found his anterior node, his thumb applying a firm pressure to it. Sideswipe’s hips danced, his thighs trying to snap together, but hooked as they were on Ratchet’s legs, he couldn’t. All he could do was sit there and tremble, his valve lips quivering, his nodes pulsing.   
  
The spray moved closer, deeper still. He swore he felt it drumming on his ceiling node. His ventilations came in sharper, faster bursts. All he could feel was heat, brimming from his frame, echoing from Ratchet behind him.   
  
Sunstreaker pressed even closer, his lips brushing over the curve of Sideswipe’s jaw, mouth still out of reach.   
  
Sideswipe whined, trying to capture Sunstreaker’s lips, but his brother was still having none of it. Instead, Sunstreaker’s thumb worked circles on Sideswipe’s anterior node, rubbing him into a fine frenzy.   
  
“Come on, Sides,” Ratchet murmured as his denta left teasing imprints on Sideswipe’s cables, the brief ignition of pain swept away in an onslaught of pleasure.   
  
He squeezed Sideswipe’s spike, pulling from root to tip and back again, hands skimming over every nodule on Sideswipe’s spike. Fingers drew bursts of charge to the dermal surface, making Sideswipe jerk and writhe.   
  
“Do it,” Sunstreaker growled against his jaw, his lips skimming a charged path toward Sideswipe’s audial. “Overload. Now.”  
  
Sunstreaker’s hand twitched. The sprayer shifted just so, and ahhh, there it was. Sideswipe jerked, thrashing in Ratchet’s grip, as the full force of the spray washed over his ceiling node and sent his valve into spasms.   
  
His mouth opened in a cry, one glitched with static, as overload stormed through his systems, laying waste to his restraint, and claiming his frame in the name of ecstasy. His vents hissed steam, his hands clenched tightly, and he writhed in Ratchet’s grip.   
  
And finally Sunstreaker’s mouth fell over his, lips hot and wet and tasting faintly of solvent. Had he actually rinsed his mouth out?   
  
No matter.   
  
Sideswipe moaned into the kiss, greedily nipping at his brother’s lips, as both Sunstreaker’s and Ratchet’s hands extended his overload. Their fingers were so gentle on his nodes, on his array, until the spray moved away, one last pass over Sideswipe’s caudal valve node making him jerk.   
  
“Oh, Primus,” he moaned into Sunstreaker’s mouth, struggling to draw oral ventilations. “That was a good one.”   
  
“Sure sounded like it,” Ratchet purred, nuzzling against the side of his head. His hand gentled around Sideswipe’s spike, less arousing and more soothing. “Feel better now?”   
  
“Much.” Sideswipe popped a kiss on Sunstreaker’s lips before turning his head to peck Ratchet’s cheek as well. “Thanks.”   
  
“You’re welcome.” Sunstreaker leaned back and pushed himself to his feet, armor creaking as he did so. “Now we can all get clean without you jittering at the back of my processor.”   
  
“Hey!” Sideswipe unlatched his arms from behind Ratchet’s head, hissing a ventilation as his shoulders protested the strain. “I wasn’t that bad.”   
  
Ratchet’s hands landed on his hips, steadying him, as he tried to get his feet beneath him. “Yes, you were.”   
  
“You were.” Sunstreaker took Sideswipe by the elbow and hauled him to his feet with seemingly no trouble at all. “But thank you for trying.”   
  
Sideswipe jostled him with an elbow. “Anything for you, bro.” He smiled, though it was crooked.   
  
“You two gonna stop being sappy and help an old mech to his feet?” Ratchet grumbled sourly, though his field pulsed with warm affection for the both of them.   
  
Sideswipe and Sunstreaker shared a look. Then they turned as one to offer a hand to Ratchet, grinning down at him.   
  
Ratchet’s optics narrowed. A trill of suspicion floated into his field, but it was whisked away by that warm affection.   
  
“Yeah, yeah,” he said. “Love you, too.”   
  
****

**Notes for the Chapter:**

> I would like to say thank you to everyone for their very kind words and for giving this story a chance, despite the rare kink attached to it. You all gave me the energy to keep posting every chapter. Thank you all very much!


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